textproduct: Rapid City

KEY MESSAGES

- Active through mid week as a series of disturbances move through the region, with severe thunderstorms possible.

- Very hot this weekend with record high temps possible and dangerous heat Saturday and Sunday.

UPDATE

Issued at 1010 PM MDT Mon Jul 6 2026

Forecast remains mostly on track this evening. Main concern for the overnight hours will be elevated convection. Currently the surface boundary runs from northeastern SD, down into southwestern SD, and central WY. A mid- level impulse is supporting elevated convection behind the boundary in northeastern WY down into Fall River county. Shear is too weak to see much in the way of organized convection, however storms will be capable of strong wind gusts as they traverse northeast in the overnight hours. Attention then turns to the severe storm potential for Tuesday, as the boundary lies mostly stationary over the forecast area. Storms expected to develop in the afternoon. Best shear lies in the northern half of the FA Tuesday afternoon, with 0-6km showing between 40-50 kts. Coupled with CAPE values in the 1000-2000 j/Kg range, will support potential for isolated to scattered severe storms in the afternoon and evening.

DISCUSSION

(This Afternoon Through Sunday) Issued at 1118 AM MDT Mon Jul 6 2026

Impulse filled westerly flow will be in place over the region through mid week as a frontal boundary stalls over the region. Near daily chances for thunderstorms can be expected with severe storms possible at times. Tues looks to be the best chance for severe storms as appreciable CAPE and moderate bulk deep layer shear will be in place. Frontal boundary has shifted south through most the FA this morning and will hang up in scentral SD. Sfc based TS will be possible along the front this afternoon as diurnal heating allows the cap to be overcome. Further west, isolated TS will be possible over the central and southern BH where eddy convergence will be in place with increasing moisture behind the front. Convection will wane across these areas into the evening. However, an upper level impulse will support pos theta-e adv across northeast WY overnight, with a complex of storms possible, as hinted at in hires models. Storms will carry across NW SD overnight into Tue morning. Sfc front will be stalled across the FA Tue, the location of which will be dictated by outflow from storms to the north. Moderately strong impulse will kick out of WY/MT in the the afternoon and evening and will drive CI there. Storms may also fire along the front if capping can be overcome, the strength of which varies in forecast models (capping that is). Given progged ML CAPE of 1-2 KJ/KG, deep bulk layer shear of 40 to 50 knots, expect supercells to be possible with strong rotating updrafts, capable of producing large hail and damaging winds. In addition, given ESE flow INVOF of the sfc front, there will be a small chance for tornadoes. Storms will carry across the region through the evening. More storms are possible Wed and Thur as sufficient LL moisture will be in place with weak stability and additional impulses. Upper ridge builds into the region this weekend, with dry and hot conds expected. Impressive temps of 35 to almost 40C at h85 with close to 6000 H5 heights over WY, will offer record to near record highs well into the 100s with 110 to 115 possible on portions of the Plains, esp Sunday.

AVIATION

(For the 12Z TAFS Through 12Z Wednesday Morning) Issued At 545 AM MDT Tue Jul 7 2026

MVFR cigs are in place over KRAP and the plains surrounding the Black Hills for a few hours this morning. Many sources of guidance are not modeling this well and confidence is low on exactly how quickly it will burn off, but current thinking is around 15z/9am with diurnal heating. Attention then turns to the potential for strong to severe thunderstorms to develop across the region starting as early as 21z/3pm. Ongoing TEMPO for KRAP and PROB30 for KGCC look good, but tweaked local timing based on the latest CAMs and also increased wind potential with thunderstorms as the HREF ensemble wind gust max and forecast soundings are showing numerous cores and outflows potentially exceeding 40-45kts. Storms this afternoon and evening could produce large hail, damaging winds, and even a tornado or two. Big picture, the strongest and most widespread activity is expected through 04-05z/10-11pm, with a stray storm or showers potentially lingering a bit later into the night. Expect sudden drops to at least MVFR cigs/vsbys near and under thunderstorm cores. Conditions trend quieter and VFR overnight tonight, but some lower clouds may try to build across the South Dakota plans westward toward KRAP near or just beyond the end of the current TAF period Wednesday morning.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.